Tv will not turn on

I had to replace the power board in my tv three weeks ago, everything worked fine until today. I went to turn the TV on and nothing happened, no power outages last night, worked fine 12 hours ago, any idea?
Thanks,

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Fault with the main power supply regulator section. Either it will be on a separate board, or on the part of its main board. Check and replace damaged component/s at its main power regulator [SMPS] section circuit. Contact any service technician. If you wish to get some details; check the site linked here. Surf the site with patience. Pull up older posts. http://electronicshelponline.blogspot.com/It will be best to replace the power supply regulator board as card basis rather than making "Surgery" to it; which usually will make loss for both money and time. Even though you can make it right, it will cost around an amount equal to the cost of a new board; including the cost of (spare parts + service charge) More to say, most of the spare parts to it will be difficult to get from open electronic spare part market. This is true to most of the flat panel TV power supply boards; irrespective of its brand and screen size.

The tv power supply board it got short and already dead some how,tv have clicking noises mean ur tv power supply board are not stable and not regulating high voltages to the rest of the tv other boards.The tv power supply board that the board where the a/c power cord plug into it.Tries websites like Shopjimmy.com,Ebay.com to buy a whole new refurbish tv power supply board for the replacement.

same problem , goes in to safety mode to prevent any more damage to the set. tech was able to get a picture colours all over the place replaced conversion parts on board went fine for 2 weeks then the same would not turn on , came on by its self colours all over the place smelt burning . back to square one.
Tech arrives again today doesn't look good this a $8500 tv
4 years ago and i'll have to pay the tip fee.
Samsung 165cm rear projection tv.good luck

It definitely does not seem to be a problem with the Picture Tube. More like a cold solder. It is definitley not a job for a layman. Also, get a good technician to have a look, as locating cold solders is a labourous and time consuming process. It could also be possible that the main DC filter capacitor is getting dry, and may require replacement.